Mr Snow said the family "remain hopeful that one day Sajid will appear but at the same time we're five years down the line and they always have at the back of their minds that something may have happened to him".

On Valentine's Day in 2007, Mr Siddique's wife Asma, who lives in Heaton, became worried when he failed to pick up his two-year-old daughter Salihah from nursery.

By late afternoon she phoned the police and they discovered his Volkswagen Bora in the car park at the Asda supermarket in Shipley.

The business associate Mr Saddique met that morning was questioned by officers but no action was taken.

Asma Siddique said in 2008 she had to stay strong for her children

Now, in a renewed attempt to get answers, Mr Snow's team are interviewing witnesses again and reviewing all evidence gathered over the past five years.

The detective said he believed at least one of the people spoken to by officers after Mr Siddique's disappearance was withholding information, possibly out of fear.

"If people are reluctant or scared to speak to the police they can ring Crimestoppers anonymously, or speak to me directly."

Reported sightings of Mr Siddique in Dubai, where he may have bought property, and in the Far East, remain unconfirmed and there have been no signs that he is alive and well.

Mr Snow said he wanted to solve the case so Mr Siddique's family could get a sense of closure, from knowing where he was or what had happened to him.

"We always hope to find someone alive, that's why we always continue with the investigation and will always follow up new lines of information that present themselves.

"Clearly this anniversary is a key time for his relatives who still seek answers as do we."